1. Field of the Invention
The present invention pertains to metal forming machines. More particularly, the present invention pertains to metal forming machines for bending metal about an aperture formed in the metal. Even more particularly, the present invention concerns metal bending machines particularly adapted for bending tabs about a window opening formed in sheet metal.
2. Prior Art
As is known to those skilled in the art to which the present invention pertains, metal bending and/or deformation operations to effect certain shapes, bends, etc., in metal objects, as well as attachments thereto, such as is encountered with door panels and the like, is a highly developed and sophisticated art. Yet, with thin sheet metal, such as vehicular exterior skins and the like, during post stamping and bending operations, there is a tendency for the thin sheet metal to be crimped, dented, scarfed or deformed. Although this may not create an impediment to the subsequent use of the product in certain situations, ordinarily where coatings, such as high gloss paint or the like is applied to the metal, any deformation in the metal may become highlighted thereby diminishing the utility of the product. As noted, this is especially true with automotive door panels, which is the first place, where potential buyers look for defects.
As detailed below, the present invention has particular utility in connection with automotive door panels and similar type structures.
Automotive door panels are fabricated from thin sheet metal in which a central opening is formed and which defines, ultimately, the opening in which is mounted the window. In developing a "window" in the opening, ordinarily, a pair of spaced apart door panels are used with the requisite "hardware", i.e., window track, motor or regulator, etc., disposed in the cavity between the panels. Also, a seal or weather strip, as well as a drip rail or the like is, usually, disposed about the perimeter of the opening. The weather seal, glass assembly and/or drip rail are enveloped by, and held in place by tabs which are, usually, welded into place, as a tab strip, around the window opening after the sheet metal is stamped out. Thus, these tabs are circumferentially disposed, perimetrally about the window opening. Prior to installing the weather strip, window assembly, etc., the flange or strip onto which the tabs are formed or provided is bent to accommodate installation of the appropriate hardware to be disposed about the window opening. Heretofore, this tab-bearing flange bending process has had the tendency to deform the sheet metal. The present invention is defined by a metal forming machine which, as is detailed subsequently, alleviates this problem. However, it is to be understood that although the present invention is described with reference to a tab bending procedure the principles and concepts upon which the present invention is predicated are applicable to any type of metal forming process where bending and/or piercing of the metal is desired.